Explanation:Cold, distant, Pluto is the only planet in our Solar System which
has not been visited by a spacecraft from Earth.
The story goes that the legend
"Pluto Not Yet Explored" on a
US postal stamp
depicting the tiny, mysterious world inspired a JPL employee
to develop plans for a Pluto flyby. These plans evolved into the current
"Pluto Express" mission intended for launch early in the next decade.
The type of small, high-tech spacecraft proposed
is depicted above in an artist's vision approaching
Pluto's mottled surface. A tenuous, transient atmosphere is visible as
blue haze beyond the bright limb
while Pluto's companion Charon looms in the distance.
Images and data from such a mission would be an incredible
boon to those
studying these bizarre, inaccessible worlds as evidence mounts that
Pluto itself is only the largest of many small ice dwarf
mini-planets. Some have dubbed the yet unexplored
Pluto-Charon system the last "astronomers' planet".
Note: Pluto's discoverer, astronomer Clyde Tombaugh, celebrated his
90th birthday on February 4.